某船用高纯锌牺牲阳极,未起到对传热管的保护作用。采用宏观测试、组织分析及电化学性能测试等方法对牺牲阳极的失效原因进行了分析。结果表明: 牺牲阳极表面有1~2 mm厚的非金属沉积物，主要为碱式氯化锌，沉积物造成了牺牲阳极表面绝缘;牺牲阳极组织中有大量富铁的析出相，与高纯锌标准严重不符;牺牲阳极在短时间运行后，发生自腐蚀，表面有附着物快速生成;阳极中铁、铜及铅等有害元素严重超标，形成了有害的第二相，使得牺牲阳极易产生自腐蚀，导致表面沉积物的形成。

Pure zinc sacrificial anodes didn't play a role in a heat transfer tube syetem. The failure reason of sacrificial anodes was analyzed by means of appearance analysis, microstructure study and electrochemical methods. The results showed that there was 1-2 mm non-metalline sediments on the sacrificial anode surface, the main composition of the semdiment was basic zinc chloride which made the surface of sarcrifical anode insulated. It was found that there was a large amount of iron rich precipitates in the microstructure of sacrificial anode, which is not in conformity with the high purity zinc standard. The self-corrosion of the sacrificial anode was detected in a short run, and the surface deposit of the sacrificial anode was rapidly generated. The contents of iron, copper, lead and other harmful elements in the anode were overweighted seriously which led to the formation of harmful second phase, and the self-corrosion was easy to produce in sacrificial anode, resulting in the formation of surface sediments.